To produce porous layers out of silicon and silicon carbide; the use of electrochemical anodization processes using hydrofluoric acids, for example, as an etching medium, is discussed in U.S. Pat. No. 5,376,241 A, for example. This method has decisive disadvantages, since on the one hand it requires a comparatively high electric conductivity of the layer to be porosified, and on the other hand the etching medium is present as a fluid. The relatively high electric conductivity is a severe restriction in particular for silicon carbide, since this material system can be doped only with great technical effort. The presence of the etching medium as a fluid and the associated inherent surface tension of the etching medium limits the minimum pore sizes that are able to be produced during porosification. A further disadvantage of the known porosification method is the unavoidable handling of hydrofluoric acids, which results in an enormous potential for danger.